I. Field of the Invention
The present invention relates to a dental impression tray.
II. Description of the Prior Art
One type of previously known dental impression trays comprises a pair of spaced sidewalls which form a channel therebetween. The side walls are attached together at one end by a cross brace. Furthermore, typically the sidewalls together with the cross brace are of a one piece plastic construction.
A layer of gauze also extends between a midpoint of the sidewalls and thus divides the channel into a first and second subchannel. In use, both subchannels are filled with a settable impression material, such as silicone, and the impression tray is positioned between the upper and lower teeth of the patient. Thus, when the patient bites into the tray channels and retains the bite until the impression material has set, a dental impression of the patient's teeth is made in the impression material.
One disadvantage of these previously known impression trays, however, is that the sidewalls are not rigidly secured to each other and, for that reason, can flex when the dental impression is being made. Such flexing can, for example, be caused by interference between the tray and the patient's gums. Furthermore, upon removal of the tray from the mouth, the sidewalls of the impression tray revert or bend back to their former or unstressed position which results in an inaccurate impression of the patient's teeth. Such inaccuracies in the old create inaccuracies in the bridge, crown or the like which is formed from the mold and requires excessive chair time for the dentist to correct. Furthermore, in some cases, the inaccuracy of the bridge work is so great that new bridge work must be constructed.
A still further disadvantage of these previously known dental impression trays is that such previous impression trays are incapable of measuring the bite tracing of the patient which is representative of the normal range of bite of the patient due to the mobility of the jaw. Without such bite tracing, interference between the patient's upper and lower teeth can occur even when the dental impression is properly made.
A still further disadvantage of these previously known dental impression trays is that, since both sides of the tray are filled with a dental impression material, a relatively large amount of impression material is required for each dental impression. Such impression material is relatively expensive and increases the overall cost of making the dental impression.
A still further disadvantage of these previously known trays is that, due to the relatively flexible construction of the tray, the impression material is oftentimes inadequately forced around the patient's gum when the impression is taken. When this occurs, it is necessary to retake the impression.